1. Technical Field
The present invention relates to a gold concentrate recovery system and a gold concentrate recovery method for recovering gold concentrates from gold ores containing gangue minerals or sulfide minerals.
2. Related Art
There are various concentration methods adopted for recovering concentrates from ores. For example, a gold ore concentration method currently employed crushes gold ores, and pulverizes the gold ores into particles having an appropriate particle size. The recovered concentrate particles are suspended in cyanide solution to leach gold. This method is called a cyanide process, by which process gold is separated from gangue minerals or sulfide minerals and concentrated. Another method currently employed initially separates gold concentrates from gangue minerals or sulfide minerals by gravity concentration and flotation, and then further separates and concentrates gold by using the cyanide process.
According to the cyanide process performed in these methods, entire gold contained in coarse ore particles is difficult to be dissolved. In this case, gold recovery is insufficiently achieved.
For overcoming this drawback, a technology of table gravity concentration (also called flowing film concentration) is proposed as a method for recovering high-grade gold concentrates. This method achieves direct refinement only by performing gravity concentration (for example, see Patent Literature 1). In addition, such a technology is proposed which automates control of a partition plate by combining the foregoing table gravity concentration and an image processing technology (for example, see Patent Literature 2).
FIG. 24 illustrates the principle of the table gravity concentration. This concentration is a method using a shaking table 102 provided with a plurality of riffles 103, and supplies ore slurry from an ore supply launder 104 to the shaking table 102 in the width direction of the shaking table 102 while oscillating the shaking table 102 in the extension direction of the riffles 103 by using a shaking driving mechanism 111. The ore slurry is produced from a mixture of ores pulverized into ore particles, and water added to the ore particles. This method further supplies additive water from a water supply launder 105 in the width direction of the shaking table 102 as indicated by arrows 160 in FIG. 24.
In this case, low specific gravity ore particles having low specific gravity such as gangue minerals and sulfide minerals contained in the ore slurry supplied to the shaking table 102 go over the riffles 103 by the flow of the additive water supplied from the water supply launder 105 independently from the oscillation movement of the shaking table 102. Then, these low specific gravity ore particles fall toward a front side surface 102c of the shaking table 102 as indicated by arrows 150a, 150b, and 150c in FIG. 24, and are recovered as tailings into a first tailing recovery storage tank 108.
On the other hand, high specific gravity ore particles having high specific gravity shift in the extension direction of the riffles 103 in accordance with the oscillation movement of the shaking table 102, and flow out of the riffles 103 into a flat area 112 where the riffles 103 are not provided. Ore particles having large particle diameters are more likely to shift in the water flow direction of the additive water (width direction of the shaking table 102) by the flow of the additive water supplied from the water supply launder 105 or by others than ore particles having small particle diameters when the specific gravity of these large particle diameter and small particle diameter ore particles are the same. Accordingly, a stream 140a of high specific gravity, small particle diameter, and high gold grade ore particles, and a stream 140b of high specific gravity and large particle diameter ore particles are formed in the flat area 112. The stream 140a of high specific gravity, small particle diameter, and high gold grade ore particles is separated from the stream 140b of high specific gravity and large particle diameter ore particles by using a partition plate 107. The high specific gravity, small particle diameter, and high gold grade ore particles are recovered as concentrates into a concentrate recovery storage tank 110, while the high specific gravity and large particle diameter ore particles are recovered as tailings into a second tailing recovery storage tank 109. The part forming a stream of high gold grade ore particles is called a gold line.
The gold concentrates recovered by this method are directly smelted and casted, and produced into ingot products (called dore as well) having a purity of 90% or higher.